1. Field of the Invention
This invention relates generally to two-dimensional optical scanners, such as for use in displays. More particularly, this invention relates to two-dimensional optical scanners that use multi-faceted rotating scan disks.
2. Description of the Related Art
Two-dimensional optical scan systems can be used in a variety of applications. For example, they can be used to scan an optical beam over a specified area in order to generate a two-dimensional display. As another example, they can be used to scan the field of view of a detector (or detector array) over an external scene, thus allowing the detector to capture a two-dimensional image of the scene. In both of these examples, the optical system may be required to produce a high-resolution image, with short exposure periods and a large image area to be covered. As a result, the two-dimensional scanners used in these optical systems can be complex and/or costly.
For example, in the case of large screen HDTV displays that are suitable for projection use in conference rooms, the high screen resolution combined with short frame periods and high screen brightness levels typically results in complex and costly scan systems. One example design is described in Published U.S. Patent Application No. 2002/0050963, “Light Beam Display with Interlaced Light Beam Scanning” by Conemac and Ford. This HDTV display system uses a high performance polygon scanner to produce the horizontal line raster scan. Two high performance, interlaced galvanometer scanners are used in conjunction with two arrays of high intensity laser diode sources to produce the vertical field scan. The laser diode sources, galvanometer scanners and polygon scanner are carefully aligned and synchronized in time in order to generate the display.
As an example of electro-optical camera systems, cameras for the infrared spectrum have been designed based on a large variety of complicated opto-mechanical scan systems. Two examples are the internal-bowl-scanner and the pyramidal polygon scanner. However, the scan resolution of these devices is limited by the limited number of scan facets that can be placed on the scan mechanisms and by the limitations on numerical aperture (NA) imposed by the scanning facet geometries.
Thus, there is a need for improved two-dimensional optical scan systems, including those that are suitable for use in high-resolution (e.g., HDTV) display systems and/or high-resolution electro-optic imaging systems.